FIG. 11 is a schematic view showing a conventional ejector cycle, wherein a numeral 10 designates a compressor, a numeral 20 is a heat exchanger, a numeral 30 is an evaporator, and a numeral 50 is a gas-liquid separator. In this conventional ejector cycle, a bypass passage 70 and a passage changeover valve 91 such as a three way valve are provided, so that the refrigerant bypasses the ejector 4 when an input amount of the refrigerant to be supplied to the ejector 4 becomes lower.
In case of a bypass flow of the refrigerant bypassing the ejector 4, a refrigerant passage is changed over by the passage changeover valve 91, so that the high-pressure refrigerant discharged from the heat exchanger 20 flows into the bypass passage 70. Then the refrigerant flows through a restriction valve 51, at which the high-pressure refrigerant is depressurized and expanded, and through the evaporator 30, at which air is cooled down, and flows into the gas-liquid separator 50. In FIG. 11, a numeral 52 designates a check valve to prevent the high-pressure refrigerant from flowing back from the bypass passage 70 into the gas-liquid separator 50. A numeral 60 is an inside heat exchanger for heat exchanging between the high-pressure refrigerant discharged from the heat exchanger 20 and the low-pressure refrigerant to be sucked into the compressor 10.
FIG. 12 is a schematic view showing a conventional ejector cycle used in a heat pump air-conditioning apparatus, wherein a numeral 80 designates a heat exchanger for a heating operation, and a numeral 81 is a depressurizing valve for depressurizing the refrigerant. The heat exchanger 80 and the depressurizing valve 81 are provided at a downstream side of the compressor 10, wherein inside air is heated at the heat exchanger 80 by heat exchanging between the compressed refrigerant from the compressor 10 and the inside air. A three way valve 92 is provided between the ejector 4 and the heat exchanger 30 for a cooling operation, the three way valve 92 (on a suck-in side) is connected with the three way valve 91 (on an ejecting side) by a refrigerant passage, in which a restriction valve 93 is provided.
According to the above ejector cycle, the refrigerant simply flows through the heat exchanger 80 and the depressurizing valve 81 during the cooling operation, and the heat of the refrigerant is radiated at the outside heat exchanger 20. Then the refrigerant is depressurized at the ejector 4 and the low-pressure refrigerant is sucked from the heat exchanger 30 for the cooling operation. In the case that the cooling operation is performed in which the refrigerant bypasses the ejector 4, the refrigerant is depressurized at the restriction valve 93 through the three way valve 91 and supplied to the heat exchanger 30 through the three way valve 92. In the case that the heating operation is performed, the air is heated at the heat exchanger 80 by the high-pressure and high-temperature refrigerant compressed at the compressor 10. The refrigerant is then depressurized by the depressurizing valve 81, absorbs the heat from the outside air at the heat exchanger 20, and simply flows through the ejector 4.
The inventors of the present invention applied for another patent application (Japanese Patent Publication No. 2003-90635), which discloses an ejector cycle. In the ejector cycle, a bypass channel is provided in the ejector, so that the high-pressure refrigerant discharged from a heat exchanger bypasses a nozzle of the ejector, and a bypass passage is provided to supply the refrigerant to an evaporator to remove frost at the evaporator. In the ejector, a valve for opening and closing the bypass channel is operated by an actuator, which also drives a needle valve for adjusting an opening area of the nozzle.
In the above mentioned prior arts, namely the refrigerating cycle with the ejector, however, it is a drawback in that a sufficient cooling performance can not be obtained when an input amount of the refrigerant to be supplied to the ejector is low and thereby a sufficient amount of the refrigerant is not supplied to the evaporator, in those cases that an outside temperature is low, a wind speed at a front side of the outside heat exchanger is high, or an inside temperature is high.
And the above Patent Publication No. 2003-90635 does not either specifically disclose or imply an idea for increasing the cooling performance or obtaining a sufficient cooling performance when the input amount of the refrigerant to the ejector is low.
Furthermore, in the conventional ejector cycle, it is another drawback in that a heating operation is not sufficiently performed due to a large pressure loss at the ejector, when the ejector cycle is used in the heat pump type air-conditioning apparatus.